Start with a clean installation of MW3 (typically the Dedicated Server tools from Steam).
: To host a co-op game, click Single Player > Start as Host . Clients can join by entering the host's IP address and clicking Start as Client .
Apply the specific 1.4.382 update files to the game directory, overwriting the official executable to ensure the client can hook into the game. Client Integration:
The patch supports all released DLC maps and modes, provided the assets are present in your game folder.